All the World's a Battlefield

Discuss here.

The zombie apocalypse has come.
The world, now a remnant of what was.
Everything civil is gone.
There is no money.
Precious metals mean nothing anymore.
In a dilapidated world, the only precious resource is food and water.
You are a survivor in this strange world.
Recently, you found a sign of sentient life.
Determined and with your trusty baseball bat, you set out into the world.

System planned out.

HOLY MECRIMINYJESUS.

Movement engine is horribly slow. It takes a full second to move now.

On the other hand, you can modify all of the graphics in the game, you can make any size map you want now (including obstacles), your player can climb stuff now, there's enemies, and YOU CAN TAKE COVER BEHIND BUILDINGS AND WALLS.

Trying to speed up the game now.

Unfortunately, me using string is slowing the damn thing down.
I just thought of something but that only speeds of the calculations...
It's the accessing of the Strings that makes things slow...

There may not be a way to optimize this one for speed, gentlemen...